Chronic Kidney Disease

CKD Basics - Tiny Kidneys, Big Trouble

• Definition: Kidney damage OR GFR < 60 mL/min/1.73m² for ≥ 3 months.
• Pediatric Focus:
  • CAKUT (Congenital Anomalies of Kidney and Urinary Tract) is the primary cause.
  • Growth failure & hypertension are key complications.
• KDOQI Staging (GFR in mL/min/1.73m²):
  • Stage 1: GFR ≥ 90 (with kidney damage)
  • Stage 2: GFR 60-89 (mild ↓)
  • Stage 3: GFR 30-59 (moderate ↓)
  • Stage 4: GFR 15-29 (severe ↓)
  • Stage 5: GFR < 15 or dialysis (kidney failure)

⭐ The most common method for eGFR estimation in children is the Schwartz formula, which relates eGFR to height and serum creatinine.

• Formula: $eGFR = k \times \frac{Height (cm)}{Serum Creatinine (mg/dL)}$.

• Early Clues: Often subtle; e.g., polyuria, enuresis, poor growth.

CKD Causes - The Usual Suspects

• CAKUT (Congenital Anomalies of Kidney & Urinary Tract): Most common (~50% of peds CKD)
  • Renal dysplasia/hypoplasia
  • Obstructive uropathy (e.g., PUV, UPJ obstruction)
  • Reflux nephropathy (VUR)
• Glomerulonephritis (GN): Significant group (~15-20%)
  • FSGS (common in SRNS)
  • Chronic GN (e.g., IgA nephropathy, MPGN)
  • Systemic: Lupus nephritis, HSP nephritis
• Hereditary Nephropathies: Genetically determined (~10-15%)
  • Alport syndrome (COL4A defect)
  • ARPKD (Autosomal Recessive Polycystic Kidney Disease)
  • Nephronophthisis
  • Cystinosis
• Other Causes: Diverse; includes:
  • HUS (Thrombotic microangiopathy)
  • Renal vascular (e.g., RVT, RAS)
  • Severe AKI sequelae (e.g., cortical necrosis)

⭐ Congenital Anomalies of the Kidney and Urinary Tract (CAKUT) are the leading cause of pediatric CKD and ESRD in most countries.

CKD Signs & Symptoms - Spotting the Signals

• Presentation often insidious; non-specific in early stages.
• Early Clues:
  • Growth failure: frequently the first indicator.
  • Anorexia, nausea, vomiting.
  • Polyuria, nocturia, secondary enuresis (impaired concentrating ability).
  • Pallor (anemia from ↓ erythropoietin).
  • Unexplained fatigue, lethargy.
• As GFR Declines:
  • Hypertension.
  • Edema (peripheral, periorbital).
  • Bone pain, deformities (renal osteodystrophy, rickets).
  • Pruritus.
  • Neurological: headache, poor concentration, seizures (uremic encephalopathy).
  • Electrolyte imbalances (e.g., hyperkalemia, acidosis).

⭐ Growth failure is often the earliest and most prominent clinical manifestation of CKD in children, significantly impacting quality of life.

CKD Management - The Balancing Act

• Core Goals: Delay progression, manage complications, prepare for Renal Replacement Therapy (RRT).
• Key Interventions (The Balance):
  • Blood Pressure: Target <90th percentile or <130/80 mmHg. ACEi/ARBs often used.
  • Anemia: Iron, Erythropoiesis-Stimulating Agents (ESAs). Target Hb 10-12 g/dL.
  • CKD-MBD: Phosphate binders, Vitamin D sterols. Control P, Ca, PTH.
  • Growth: Recombinant human Growth Hormone (rhGH) if GFR <50 ml/min/1.73m².
  • Acidosis: Oral alkali (e.g., NaHCO₃). Target serum bicarbonate >22 mEq/L.
  • Nutrition: Adequate calories; protein, Na⁺, K⁺, P, fluid restriction as per stage.
  • Immunizations: Crucial; follow specific schedules.
• Renal Replacement Therapy (RRT):
  • Dialysis: Peritoneal (PD) often preferred in younger children; Hemodialysis (HD).
  • Transplantation: Optimal long-term solution.

⭐ Kidney transplantation offers the best long-term outcome and quality of life for children with ESRD, improving growth and neurocognitive development.

High‑Yield Points - ⚡ Biggest Takeaways

• CAKUT (Congenital Anomalies of Kidney and Urinary Tract) is the leading cause of pediatric CKD.
• Growth failure is a cardinal sign, requiring prompt intervention.
• Anemia (due to ↓ erythropoietin) is frequent and significant.
• CKD-MBD causes renal osteodystrophy, affecting growth and bone integrity.
• Hypertension is common, accelerates CKD progression and cardiovascular risk.
• Estimate GFR in children using the height-based Schwartz formula.
• Proteinuria is a key marker of kidney damage and predicts progression.